Laminated spring



Patented July 7, 1931 ETD STATES JOEL SAMUEL FRIES, OF HELENEL'UND,

PATENT OFFICE SVVEDE N, ASSIGNOR TO AKTIEBOLAGET PANY OF SWEDEN LAMINATED SPRING Application filed June 30, 1928, Serial No. 289,529, and in Sweden July '7, 1927.

The present invention relates to animprovement in laminated supporting springs of the type which consist of two or more spring leaves or plates placed on top of each other and having a substantially rectangular cross sectional shape. In order in such springs to prevent lateral displacement of the spring plates relatively to each other, said plates are often provided with longitudlnal lo projections or ridges.

The present improvement consists principally in that each spring plate is provided with longitudinal projections or ridges on both sides, said ridges having such height and such size that the maximum stresses on both sides of the spring plate become equal or substantially equal and thus become decreased as far as possible. This arrangement may suitably be carried out in such 11 manner that each spring plate is provided on one side with two longitudinal projections or ridges, one along each edge, and on the other side with two longitudinal projections or ridges at a distance from the edges such that when the spring plate is placed against a second spring plate said last mentioned projections or ridges come between the ridges at the edges of the second plate. By this engagement the ridges will thus prevent lateral displacement of the plates relatively to each other.

In the accompanying drawings, Fig. 1 shows a cross section of two spring plates having ridges as heretofore used, Whereas Figs. 2 to 5 show cross sections of various forms of springs having two spring plates according to the present improvement.

As shown in Fig. 1, it has heretofore been customary to provide each spring plate 1 49 on one side, and in the middle thereof, with a longitudinal ridge 2 which engages a corresponding groove 3 in the ad aCent spring plate when the spring plates are placed against each other. By making the spring plates with a ridge on one side and a groove on the other, in this manner, the moment of inertia with respect to the neutral line a-a suffers only a hardly appreciable change, whereas the moment of resistance 59 with which one has to calculate, is decreased to a considerable degree, so that, for instance, for a spring plate having the cross sectional dimensions 90 X 13 mm. it is decreased by no less than 29 per cent as compared with the same moment of a corresponding spring plate having a quite rectangular cross section, without ridge or groove. The capacity of the spring is therefore decreased by no less than about per cent, and breaks will easily occur at the top of the ridge 2 since at this point the fiber stress becomes very great These difliculties are remedied by the present invention.

In the embodiment of the invention illustrated in Fig. 2, each spring plate 4; is provided on one side with two longitudinal pro- JQCtlOIlS or ridges 5, one at each edge, and on the other side with two longitudinal projections or ridges 6 which are located at such distance from the ed es of the spring plate that, when the spring plate is placed against another spring plate, said ridges 6 on the first plate come between the ridges 5 at the edges of the second spring plate. Through this engagement the ridges 5 and 6 will thus prevent lateral displacement of the spring plates relatively to one another, in the same manner as the ridges 2 and grooves 3 in Fig. 1.

In the construction shown in Fig. 2 the ridges 5 have the same width and height as the ridges 6, as a result of which the distance I) from the upper face of the ridges 5 to the neutral line aa becomes equal to the distance 0 between said line and the lower face of the ridges 6, and the maximum stresses become equal and therefore also as small as possible on both sides of the spring. The risk of spring fracture is therefore decreased, and the capacity as well as the life of the spring are increased. In this embodiment each ridge 5 or 6 has a width equal to onesixth of the width of the entire spring plate. Tests have proved that this construction gives the best elasticity possible. The space 7 between the inner ridges 6, and which may suitably be utilized for supplying lubricant to the sliding surfaces of the spring plates, thus obtains a width equal to onethird of the entire width of the spring plate. The

Q. -down wardsl side surfaces of the ridges are preferably made with slightly different radii of curvature, in such manner that narrow spaces 8 are formed between the same which likewise may serve for supplying lubricant.

According E-Q Fig. 3, the ridges 6v on the lower ide bf a h pr ng P a iare l Same. height as the ridges 5 on its upper side, but a greater width. The neutral line ri a is, therefore, moved slightly downwards, that is, in the direction towards the wideridges' 6-, so that the distance 6 becomes somewhat greater than the distance 0'.

This is also the case in the construction illustrated in Fig. h'which only difiers from that shown in Fig. 3 in that the depth of the recess or groovefTbetween the two inner ridges 6. is "slightly decreased, which results in the neutral line being displaced still more The constructien illustrated in Fig. 5 corresponds substantially to that illustrated in Fig. 2, the ridges'fgfand 6 Fig. 5 having. equal height and width, but it' d'ifiiersv from the construction shown, in' Fig. 2 in that the width of the ridges 5 and 6 is somewhat smaller in pi'oportipn to the width of the entire spring plate.

I claim 1 In a laminated spring, the combination of at least two springvplates bearing. against each other and each having a substantially rectangular cross section, each spring plate. havinglongitudinal'ridges on both sides proj ecting outside the rectangular cross section of the'plate, said ridges on one side/of each 0, plate equal to the width of the ridges on the plate running along the edges of the plate, and sa d ridges on the other side of each plate running at a d stance from the edges oi the first named side of the plate, ridges hav; ing such height and such size that the. maximum stresses become substantially equal on both sides of the spring plate.

2. A laminated spring asclaimed in claim 1, in which each ridge has a width substantially equal to one-siitth of the width of the spring plate.

3. In a'laminated spring, the combination of atleast two springplates bearing against each other and each having a substantially rectangular cross section, each spring plate havingon' each side two, longitudinal ridges projecting outside the rectangular cross section ofthe plate and; separated-bya groove, the distance'b'etwe'en'the inner edges of the two ridges on the one side of the spring plate being substantially, equal to the width across thefouter edges of the two. ridges on the other siceof the springplate so that when one spring plate is placed against a second spring plate the inner edges of. the ridges on one side. ofthe first plate bear againstthe outer edges of the ridges on the other side of the second plate, said ridges oneach spring plate have ing such height and such size that the maximum stresses on both sides of the spring plate become substantially equal.

4:. A spring plate having a substantially rectangular cross section and having on each side two, longitudinal ridges. projecting outside the rectangular. crosssection of the plate and separated by a groove, the ridges on the one side of the spring plate being displaced relatively to the ridges on the other side or the spring plate in such nianner that a ridge on one side is not opposed by a ridge on the other side, said ridges having such height and such size that the maximum stresses on both sides of the spring plate become substantially equal.

A spring/plate having a substantially rectangular. cross section and having on each side two, longitudinalridges projecting out side the rectangular cross's'ection of the plate and separated by a groove, the distance between the inner edges of the two ridges. on the one side ofthespring 'alate being substantially equal to the Width across. the outer edges of the two ridges on the other side of the spring p late, said ridges having such height and such, size that the maximum stresses on both sides 9f the spring plate bem sub an a y equ JOEL SAMUEL 

